A self-tightening drill chuck has a chuck body, a tightening sleeve that can rotate coaxially to the chuck body, and a jaw holder supported on the chuck body in which jaws are guided in guide slots. The jaws can be adjusted by the jaw holder by a relative rotation between the chuck body and the tightening sleeve for tensioning and loosening. A locking device comprises an annular array of teeth coaxial with the chuck axis and a pawl that engages under the force of a spring into the gear ring and is supported on the jaw holder. This locking device locks the chuck body and the pawl against relative rotations for loosening the jaws when the pawl has engaged into the teeth but does not hinder relative rotation tightening. A stop formation on the jaw holder and a counterstop formation on the tightening sleeve limit relative rotation of the tightening sleeve relative to the jaw holder between a first rotational end position corresponding to the engaged state or locking position of the pawl and to a second rotational position corresponding to the disengaged state or a freeing position. A latch with a seat associated with the first rotational position and with another seat associated with the second rotational position is provided between the jaw holder and the tightening sleeve. This latch does not release rotation of the tightening sleeve relative to the jaw holder at least in the tightening direction until a predetermined tensioning force has been achieved.
Such a drill chuck is known from WO 2006/111114. It has the advantage of a simplified manipulation in comparison to earlier known self-tightening drill chucks since the user need merely grasp and rotate the tightening sleeve in order to achieve the tightening or loosening of the drill chuck as a function of the direction of rotation selected. However, it has turned out to be possible on account of the self-tightening property of the drill chuck in certain areas of application that the drill chuck can self tighten to such an extent that it can no longer be opened manually.